Some wellbores, for example, those of some oil and gas wells, are lined with a casing. The casing stabilizes the sides of the wellbore. In a cementing operation, cement is introduced down the wellbore and into an annular space between the casing and the surrounding earth. The cement secures the casing in the wellbore, and prevents fluids from flowing vertically in the annulus between the casing and the surrounding earth. Different cement formulations are designed for a variety of wellbore conditions, which may be above ambient temperature and pressure. In designing a cement formulation, a number of potential mixtures may be evaluated to determine their mechanical properties under various conditions.